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Design, fabrication, and characterization of a high-performance CMOS-compatible thermopile infrared detector with self-test function
摘要： This paper presents the design, fabrication and characterization of a CMOS-compatible thermopile infrared (IR) detector with self-test function based on XeF2 front-side dry etching. In order to achieve better performance, a heavily doped N/P-polysilicon is utilized to form thermocouples, and XeF2 front-side isotropic etching is adopted to release and thermal isolation. At the same time, a platinum thermopile IR detector. IR radiation sensing shows that the detector achieves relatively high responsivity of 160.03 V/W and detectivity of 9.75×107 cm?Hz1/2 and a extremely short response time of 2.5 ms in air at room temperature. In addition, self-test measurement is conducted and validated by applying a voltage to the heater. Compared with traditional methods for detecting thermopile performance, this method has obvious convenience and simplicity, which provides a effective way for performance monitoring of thermal-based devices.
关键词： high-performance,thermopile infrared detector,heater,self-test
更新于2025-09-23 15:21:01
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Growth Temperature and Electrochemical Performance in Vapor-Deposited Poly(3,4-ethylenedioxythiophene) Thin Films for High-Rate Electrochemical Energy Storage
摘要： Poly(ethylene 3,4-dioxythiophene (PEDOT) ?lms synthesized by oxidative chemical vapor deposition (oCVD) display strong electrochemical activity in the region from 2 to 4.2 V vs Li/Li+. By contrast, the more commonly studied PEDOT:polystyrenesulfonate (PSS) ?lms have negligible electrochemical activity in this region. For the oCVD ?lms, its small dopant anions (Cl?) that can easily enter and exit the polymer structure allow exchange with the Li+ counterion in solution, while for PEDOT:PSS, the poly(styrenesulfonate) dopant is a large macromolecule having substantially lower mobility. Here, we seek to elucidate the relationship between the structural characteristics of oCVD PEDOT thin ?lms and their electrochemical properties, particularly in Li-ion electrolyte systems. Speci?cally, we seek to rationally design the thin-?lm properties of oCVD PEDOT for high-rate performance and cycle life by varying the ?lm growth temperature. We observe that the dominant e?ect of increasing growth temperature is an in situ reorganization to an edge-on ?lm texture. In this case, the π?π stack is perpendicular to the substrate surface. The alternative dominant texture is face-on dominance, where the π?π stack is parallel to the substrate surface. For the ?rst time, we show that edge-on dominant ?lms provide higher speci?c capacities for a given charge/discharge rate. Furthermore, Raman spectroscopy demonstrates that edge-on dominant ?lms are less susceptible to oxidative damage after long-term cycling. This also enables edge-on dominant ?lms to maintain lower charge-transfer resistances compared to identically cycled face-on ?lms. Edge-on oCVD PEDOT is paired with molybdenum disul?de to demonstrate thick, optimized oCVD PEDOT thin ?lms in asymmetric devices for high-rate electrochemical energy storage.
关键词： electrochemical doping,oCVD,electrochemical energy storage,PEDOT,high-rate performance,conductive polymer
更新于2025-09-23 15:21:01
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Natural Sugar Assisted Chemically Reinforced Highly Durable Piezo-Organic Nanogenerator with Superior Power Density for Self-Powered Wearable Electronics
摘要： Natural piezoelectric material is of increasing interest particularly for applications in biocompatible, implantable, and flexible electronic devices. In this paper we introduce a cost effective, easily available natural piezoelectric material, i.e., sugar in the field of wearable piezoelectric nanogenerator (PNG) where low electrical output, biocompatibility and performance durability are still critical issues. We report on a high performance piezo-organic nanogenerator (PONG) based on the hybridization of sugar encapsulated polyvinylidene fluoride (PVDF) nanofiber webs (SGNFW). We explore the crucial role of single crystal sugar having fascinating structure along with the synergistic enhancement of piezoelectricity during nano-confinement of sugar interfaced macromolecular PVDF chains. As a consequence, the SGNFW based PONG exhibits outstanding electricity generation capability (for example ~100V under 10 kPa human finger impact and maximum power density of 33 mW/m2) in combination with sensitivity to abundantly available different mechanical sources (such as wind flow, vibration, personal electronics and acoustic vibration). Consequently, it opens up suitability in multifunctional self-powered wearable sensor designs for realistic implementation. In addition, commercially available capacitors are charged up effectively by the PONG due to its rapid energy storage capability. The high performance or the PONG not only offers the “battery free” energy generation (several portable units of LEDs and a LCD screen are powered up without using external storage) but also promises its use in wireless signal transmitting systems that widens the potential in personal health care monitoring. Furthermore, owing to the geometrical stress confinement effect, the PONG is proven to be a highly durable power generating device validated by stability test over 10 weeks. Therefore, the organic nanogenerator would be a convenient solution for portable personal electronic devices that are expected to operate in a self-powered manner.
关键词： self-powered electronics,PVDF,organic piezoelectric nanogenerator,high performance and durability,Natural piezoelectric material,sugar
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE 5G World Forum (5GWF) - Silicon Valley, CA, USA (2018.7.9-2018.7.11)] 2018 IEEE 5G World Forum (5GWF) - Multipath Propagation Analysis of 5G Systems at Higher Frequencies in Courtyard (Small Cell) Environment
摘要： The main target of this paper is to study the propagation characteristics of an outdoor and indoor user utilizing 5G system at higher frequency in a courtyard surrounded by building walls i.e. small cell environment. This research work is carried out by doing 3D ray tracing simulations utilizing “sAGA” – a 3D ray tracing tool. Unlike the conventional cellular network frequencies, the considered frequencies in the scope of this work are 15 GHz, 28 GHz and 60 GHz. For simulation routes, the results are provided in the form of received signal strength. For static points, the results are presented in the form of power angular spectrum and power delay profile. The achieved simulation results show that an adequate outdoor and indoor service can be provisioned at the considered frequencies. However, it is challenging to provide services to indoor user at 60 GHz using an outdoor base station even in such a small cell environment.
关键词： 3D ray tracing,multipath propagation,small cell,system performance,millimeter wave frequencies,5G
更新于2025-09-23 15:21:01
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Study of road tunnel threshold zone lighting reduction coefficient; 公路隧道入口段亮度折减系数研究;
摘要： The luminance in the road tunnel threshold zone attracts broad attention due to its enormous energy consumption and direct influence on tunnel transportation security. Current lighting design methods in threshold zones mostly adopt the reduction coefficient method. However, the determination of reduction coefficient k simply considers tunnel design speed and flow rate, while excluding outside tunnel luminance and threshold zone color temperature and luminance, which have a major impact on driver visual adaptation. Existing problems in the determination of k value are analyzed; a visual performance experiment is utilized; and the reaction time of drivers in changeable outside tunnel luminance and threshold zone color temperature and luminance conditions is obtained; thus, the equations concerning reduction coefficient variation law are derived. In the end, a comparative analysis is made of the k values of the reduction coefficient stipulated by various norms under different color temperature conditions.
关键词： reaction time,threshold zone,visual performance,reduction coefficient,tunnel lighting
更新于2025-09-23 15:21:01
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Planning of Geo-Distributed Cloud Data Centers in Fast Developing Economies
摘要： In recent years, with the rapid development of big data, artificial intelligence and cloud computing, the construction of cloud data centers has entered into a fast-growing period, especially in fast developing economies. The placement for geo-distributed cloud data centers has a great impact on costs and performance. In this paper, we propose a framework to determine the optimal placement of geo-distributed cloud data centers, taking into considering both cost minimization and network performance. In we apply this framework to the placement to cloud data centers in China. We show how the DC placement may be affected by network performance requirements. We also show how factors like population mobility and adoption of clean energy, typical in fast developing economies, may affect DC placement. We research provides insights to the long term DC planning in fast developing economies.
关键词： network performance,fast developing economies,geo-distributed cloud data centers,cost minimization
更新于2025-09-23 15:21:01
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[IEEE 2018 12th France-Japan and 10th Europe-Asia Congress on Mechatronics - Tsu, Japan (2018.9.10-2018.9.12)] 2018 12th France-Japan and 10th Europe-Asia Congress on Mechatronics - Potentials of Galilean and Keplerian Liquid Crystal Zoom Lens System
摘要： This paper focuses on a non-mechanical zoom lens system using Liquid Crystal (LC). The LC lens cell is well known as an optical device of which the focal length can change non-mechanically as a lens by small electric power. The authors apply the two LC lens cells for composing the zoom lens system in which the magnification can change continuously in this paper. As two representative types of the telescopic lens, the Keplerian and the Galilean are famous. The former combines two convex lenses, while the latter combines a convex lens and a concave lens. The range of the focal length of which the LC lens cell can change is definite. It depends on the lens power, which is defined as an inverted value of the focal length. In this study, potential performances of the magnification range as the zoom lens, from the minimum to the maximum, have been estimated by simulation, comparing between the Keplerian and Galilean types. In addition, requirements of the lens power of the LC lens has been estimated. The authors have also discussed their smallest realizable size of the LC zoom lens system from the above simulation results.
关键词： Keplerian,the smallest size,potential performance,non-mechanical zoom lens,Galilean,liquid crystal zoom lens
更新于2025-09-23 15:21:01
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Effect of Mn-doping on dielectric and energy storage properties of (Pb0.91La0.06)(Zr0.96Ti0.04)O3 antiferroelectric ceramics
摘要： Bulk ceramics with high recoverable energy density (Wre) and energy efficiency (h ) play a critical role in the development of pulsed power systems for miniaturization and lightweight. The orthorhombic phase (Pb,La)(Zr,Ti)O3-based antiferroelectric (AFE) ceramics have been regarded as one of the most promising candidates for pulsed power system applications due to their relatively high energy storage density and efficiency. However, the main drawback of orthorhombic phase (Pb,La)(Zr,Ti)O3-based AFE ceramics is relatively low dielectric breakdown strengthen (DBS), which has always restricted the improvement of energy storage density. In this study, an effectively method to increase DBS by the introduction of Mn has been proposed. The relative density of orthorhombic phase (Pb0.91La0.06)(Zr0.96Ti0.04)O3 (PLZT) ceramics was improved by Mn-doping. And the introduction of Mn can decrease the tolerance factor (t) of PLZT ceramics because the radius of Mn2+ is larger than that of B-site Zr4+/Ti4+, and thus enhancing antiferroelectricity. Meanwhile, the effects of Mn-doping on the phase structure, microstructure and dielectric properties of PLZT ceramics have been studied thoroughly in this study. It is found that the highest Wre of 7.65 J/cm3 is obtained at 1.0 mol% Mn-doped PLZT ceramic, which is obviously larger than that of undoped PLZT ceramic (5.71 J/cm3). These results suggest that the Mn-doped PLZT ceramics are potential energy storage materials in pulsed power systems.
关键词： Antiferroelectric ceramics,Energy storage performance,Mn-doping
更新于2025-09-23 15:21:01
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Dual-Hop Mixed RF-UOW Communication System: A PHY Security Analysis
摘要： In this paper, the secrecy performance of a dual-hop mixed radio-frequency/underwater optical wireless communication (RF-UOWC) system is investigated. The considered system consists of one single antenna source node (S) communicating with one destination node (D), considered as the legitimate receiver, through an amplify-and-forward relay node equipped with multiple antennas for reception. Specifically, the relay receives the incoming signal from S via an RF link, applies maximal-ratio combining technique, amplifies the output combined signal with either a fixed gain or variable gain, and then forwards it to the destination via an UOWC link. The transmission protocol is performed under the eavesdropper’s attempt to overhear the RF link (i.e., S-R). We derive exact closed-form expressions for the system’s average secrecy capacity and the intercept probability in terms of Meijer’s G-function as well as the univariate and bivariate Fox’s H -functions. A complexity analysis is also performed to analyze the evaluation time of the derived analytical formulas as well as Monte Carlo simulation method complexity. Our derived analytical formulas present an efficient tool to depict the impact of some system and channel parameters on the secrecy performance, namely, the number of relay antennas, the number of eavesdropping nodes, relay gain, fading severity of RF links, and water turbulence severity of the UOWC link.
关键词： intercept probability,underwater optical wireless communication (UOWC),dual-hop relaying,physical layer security,performance analysis,Amplify-and-forward,average secrecy capacity
更新于2025-09-23 15:21:01
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Silicon as a ubiquitous contaminant in graphene derivatives with significant impact on device performance
摘要： Silicon-based impurities are ubiquitous in natural graphite. However, their role as a contaminant in exfoliated graphene and their influence on devices have been overlooked. Herein atomic resolution microscopy is used to highlight the existence of silicon-based contamination on various solution-processed graphene. We found these impurities are extremely persistent and thus utilising high purity graphite as a precursor is the only route to produce silicon-free graphene. These impurities are found to hamper the effective utilisation of graphene in whereby surface area is of paramount importance. When non-contaminated graphene is used to fabricate supercapacitor microelectrodes, a capacitance value closest to the predicted theoretical capacitance for graphene is obtained. We also demonstrate a versatile humidity sensor made from pure graphene oxide which achieves the highest sensitivity and the lowest limit of detection ever reported. Our findings constitute a vital milestone to achieve commercially viable and high performance graphene-based devices.
关键词： device performance,supercapacitors,graphene,humidity sensors,silicon contamination
更新于2025-09-23 15:21:01